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J Korean Acad Prosthodont. 2019 Jul;57(3):211-218. Korean. Original Article. https://doi.org/10.4047/jkap.2019.57.3.211
Jeong SJ , Cho HW , Jung JH , Kim JM , Kim YL .
Department of Prosthodontics, School of Dentistry, Wonkwang University, Iksan, Republic of Korea. pro11@wku.ac.kr
Dental Laboratory, Wonkwang University Dental Hospital, Iksan, Republic of Korea.
Abstract

Purpose

The purpose of the present study was to compare the accuracy of four different metal copings fabricated by CAD/CAM technology and to evaluate clinical effectiveness.

Materials and methods

Composite resin tooth of the maxillary central incisor was prepared for a metal ceramic crown and duplicated metal die was fabricated. Then scan the metal die for 12 times to obtain STL files using a confocal microscopy type oral scanner. Metal copings with a thickness of 0.5 mm and a cement space of 50 µm were designed on a CAD program. The Co-Cr metal copings were fabricated by the following four methods: Wax pattern milling & Casting (WM), Resin pattern 3D Printing & casting (RP), Milling & Sintering (MS), Selective laser melting (SLM). Silicone replica technique was used to measure marginal and internal discrepancies. The data was statistically analyzed with One-way analysis of variance and appropriate post hoc test (Scheffe test) (α=.05).

Results

Mean marginal discrepancy was significantly smaller in the Group WM (27.66 ± 9.85 µm) and Group MS (28.88 ± 10.13 µm) than in the Group RP (38.09 ± 11.14 µm). Mean cervical discrepancy was significantly smaller in the Group MS than in the Group RP. Mean axial discrepancy was significantly smaller in the Group WM and Group MS then in the Group RP and Group SLM. Mean incisal discrepancies was significantly smaller in the Group RP than in all other groups.

Conclusion

The marginal and axial discrepancies of the Co-Cr coping fabricated by the Wax pattern milling and Milling/Sintering method were better than those of the other groups. The marginal, cervical and axial fit of Co-Cr copings in all groups are within a clinically acceptable range.

Copyright © 2019. Korean Association of Medical Journal Editors.